Liquid injectable medicaments are often stored in sealed ampoules with a frangible seal or vials with elastomeric closures. Practitioners generally access the ampoules by breaking the seal, and withdrawing the liquid through a conventional hypodermic needle into a syringe. When the medicament container is a vial with an elastomeric closure, the practitioner generally uses a conventional sharp hypodermic needle on a syringe to penetrate the closure and withdraws the medicament into the syringe. Conventionally, the filled syringe with the hypodermic needle is then used to administer the medicament directly to the patient, or to penetrate a septum on an intravenous (I.V.) set and deliver the medicament to the patient through a catheter. With the wide recognition of the hazards of blood borne pathogens by the medical community, device manufacturers have developed alternatives to conventional hypodermic needles for transferring medicaments from sealed vials and administering the medicaments to patients. Alternative transfer devices include the needleless I.V. sets that incorporate pre-slit septa that are accessible by a blunt cannula. These blunt cannula/pre-slit systems are widely available from several manufacturers. While the blunt cannula/slit septum system is very useful for transfer of a medicament from an already filled syringe into an I.V. delivery system, the problem of filling the syringe from a sealed ampoule or a vial with an elastomeric closure is not solved by the pre-slit septum/blunt cannula system.
Many commonly used medicaments are supplied lyophilized and are reconstituted under sterile conditions just prior to usage. These lyophilized materials are generally supplied sterile in air-tight containers that either have a frangible seal or a monolithic elastomeric closure to protect the contents from moisture, microbial contamination, and in some cases, oxygen. These same type containers are also commonly used for aqueous solutions of medicaments. Ampoules with frangible seals and vials with monolithic elastomeric closures are not easily accessible by blunt cannula devices. As a result, device manufacturers developed filling devices known as "filling straws" or "filling spikes". These devices are somewhat similar in appearance to hypodermic needles, but have a larger diameter and bulky appearance indicative of their intended usage, i.e., puncturing of septa, not patient's tissue. The filling straws generally have a sharpened beveled point at their distal ends, but the bevel shape is generally designed to penetrate septa without coring, rather than being designed to penetrate tissue. Ampoules are generally made of glass with a weakened area that allows the practitioner to break off the top and provide access to the ampoule's contents. The filling straws are generally mounted on a syringe and have a small enough diameter and sufficient length to be used to reach into an opened ampoule and withdraw the contents. When the filling straws are used on a vial with an elastomeric closure, the beveled point is used to penetrate the closure and provide access to the contents. Since the filling straws are designed to penetrate septa and generally present a too "formidable" appearance to be used for patient's tissue penetration, they generally are used as intended by the manufacturer. A practitioner may use a filling straw to withdraw a medicament into a syringe and then remove the filling straw and attach the syringe directly to an I.V. set by utilizing a P.R.N. adapter. (P.R.N. is an acronym for the Latin term pro re nata, literally translated "as the need arises".) Alternatively, a practitioner may choose to remove the filling straw and attach a blunt cannula to the syringe, then access the I.V. set through a pre-slit septum. These alternatives generally eliminate the need for sharp hypodermic needles, but according to most hospital sharps usage protocols, the sharpened filling spike is still treated as a sharp and requires special handling and disposition.
Device manufacturers strive to simplify the usage of filling and transfer devices for practitioners. Filling straws that incorporate a blunt cannula are available. These devices have a filling straw with a distal void that accepts a blunt cannula with a shield over the filling straw. When a practitioner uses such a combination device by removing the shield, either the filling straw or the blunt cannula may be inadvertently exposed. If a device was available that prevented inadvertent exposure of the sharpened filling straw, the art of filling syringes and transfer of liquid medicaments would be advanced. Such a device is described hereinbelow.